Mechanical stoker



May 22, 1928.

S. IMAM URA MECHANICAL STOKER 3 Shee Filed Sept. 23, 1924 May 22, 1928. 1,670,358

. s. IMAMURA MECHANICAL STOKER Filed Sept. 23, 1924 3 Sheets-Sheet 2 S. IMAMURA MECHANICAL STOKER 'May 22, 1928.

Filed Sept. 25, 1924 3 Sheets-Sheet 3 Patented May 22, 1928.

UNITED STATES PATENT OFFICE.

snma'rano minimum, or msnnru, NAGOYA, JAPAN.

MECHANICAL sroxnn.

Application filed September 23, 1924, Serial No. 739,419, and in Japan October 1, 1928.

My invention relates to improvements in a mechanicalstoker and has for its object to provide a simple, efiectiveand economical stoker. y i

According to the presentinvention grate bars-are transversely arranged to form a series of fuel supporting shelves in stepped relation at a suitable inclination with air openings between said grate bars to supply air horizontally from the under side of the grate. Reciprocating pusher members are provided for each step of the grate bars and areslowly operated by a suitable reciprocating mechanism through said air" openings whereby the fuel supplied from the hopper is burned on the grate while being gradually conveyed on the steps. The upper surf-aces of each gratebar are-arranged in a plane, but for the sake of strength as well as for increasing the grate surface, the grate bars are preferably corrugated and the sliding members of triangular cross section are arranged to slide on the bottom or trough parts of said corrugations through circular openings formed on the ribs projecting at the lower sides of the grate bars. Such corrugated bars are arranged in such'a manner that the top of a corrugation of one grate bar is in vertical alignment with the troughs of the adjacent bars so that when the fuel falls from the bottom parts of the upper step it strikes ridges of the lower step and while said fuel is falling into the troughs of the next lower bar it is rolled or overturned and the combustion is thereby accelerated.

While it is known to be old in the prior art to provide grates whose surfaces are stepped and over which the fuel is gradually conveyed While burning, the present invention is characterized in that sliding members connected to a reciprocating mechanism are provided for each of the steps of the grate and the fuel on each step is simultaneously transported to thelower step and is burned by air supplied horizontally from, the air openings formed in ribs on the under sides of the bars. The fuel falls on the lower step while the sliding member is going forward on said step and the air opening is artially closed by the sliding member. lbhen the sliding member moves backward the fuel remains on the grate bar being agitated by the movement of the sliding mem her and the air opening is fully opened while the sliding member rests at its backward position, thus the combustion of the fuel is i accelerated and a considerable economy of fuel is obtained; i

The accompanying drawing shows an example of'the mechanicalstoker embodying the present invention. 1 Fig. 1 is a sectional side elevation of the stoker as applied to a. boilerfurnace. Fig. 2 is an enlarged elevation of the stoker as seen from within the furnace. Fig. 3 is a sectional side elevation of the structure shown in Fig. 2, also show-. ing in section the connections between some (if the pusher members and 'thetransverse ars.

In Fig. 1, (1) is thewall of the furnace, (2) is a boiler; (3) is a hopper for receiving coal, 4) aregrate bars or fuel supporting shelves arranged transversely keeping a.

suitable clearance between adjacent bars to form a stepped grate of some thirty degrees made in the form of thin plates, but as they are apt to become deformed owingto the elongation and contraction caused by the temperature of combustion, their upper sides are preferably corrugated as shown in Fig. 2, whereby the deformation can be avoided and atthe same time the surface area of the grate increased. Such corrugated bars are arranged in such a manner that the ridges of one grate bar are in vertical alignment with the troughs of the adjacentgrate bars as shown in Fig. 2 so that the fuel falling from the troughs of the upperstep is di vided by the angular ridges of the lower step and rolls into the troughs thereof. Each grate bar (a is provided at its lower side with a strengthening rib (5) and circular openings (6) for the supply of air are formed in said rib in horizontal alignment with the troughs of the next lower step.

The sliding members consist in rods of substantially triangular section passing freely through the air openings (6) thus leaving some clearance for the passage of air. The other ends of these rods (7) are connected by pins (8) to transverse bars (9) fixed at both ends toa frame (10) corresponding'in inclination to the steps in inclination of the grate. The frame (10) is mounted on rollers 12 which roll on the rail. (11) and is connected by a rod (13) to a crank (14:) which is slowly rotated by a Worm mechanism (15).

The width of the grate bars and the numher of steps of the grate are properly designed so that the fuel is completely burned while being conveyed to the lowermost step. The quantity of the fuel to be supplied on the grate can be adjusted by regulating the speed or number of reciprocations of the sliding member (7). An ordinary fixed rate (16) is arranged at the lower end oi the stepped grate for thoroughly burning any fuel into ash. As the volume of the fuel lessens while burning on the stepped grate, the grate bars are preferably made broader toward the lower steps, as shown in Fig. 3. Slots (17) are formed in the sliding members (7), at the lower steps, the length of the slots being gradually increased towards the bottom of the grate so that the lengths of the strokes of the sliding members for the lower steps are gradually diminished as the quantity of fuel conveyed is lessened. However, the device may use either the fixed or slotted connection with all the pusher memhers.

1. In a mechanical stoker, in combination, a plurality of fixed fuel supporting shelves in stepped relation, each of said supporting shelves being provided with troughs, the troughs of each shelf being in staggered relation to the troughs in the adjacent shelves, pusher members adapted to reciprocate in said troughs, and means for reciprocating said pusher members.

2. In a mechanical stoker, in combination, a plurality of fixed grate bars in stepped relation, each of said bars being provided with transverse troughs, the troughs in each bar being in staggered relation to the troughs in the adjacent bars, pusher members adapted to reciprocate in said troughs, and means for reciprocating said pusher members.

3. In a mechanical stoker, in combination, a plurality of fixed grate bars in stepped re lation, each of said bars being provided on its upper side with transverse troughs and on its lower side with a longitudinal rib, the troughs of each bar being in staggered relation to the troughs in the adjacent bars, air openings in said ribs, pusher members extending through said openings and adapted to reciprocate in the troughs of the adjacent bar, and means for reciprocating said pusher members.

4.111 a mechanical stoker, in combination, a plurality of fixed fuel supporting shelves in stepped relation, each of said supporting shelves being provided with troughs, the troughs of each shelf being in staggered relation to the troughs in the adjacent shelves, pusher members adapted to reciprocate in said troughs, and a reciproeating frame to which said pusher members are connected, whereby said pusher members are given a reciprocating motion.

5. In a mechanical stoker, in combination, a fuel hopper, a plurality of fixed grate bars in stepped relation, each of said bars being provided with transverse troughs, the troughs of each bar being in staggered relution to the troughs in the adjacent bars, the width of said bars successively decreasing towards the fuel hopper, pusher members adapted to reciprocate in said troughs and means for reciprocating said pusher members.

In testimony whereof I have atlixed my si ature.

SHINATARO IMAMURA. 

